First discovered by someone messing around on Google Earth, it's the largest piece of animal-built infrastructure on the planet, and according to some science people, it would have taken upwards of 20 years to build, and can be seen in satellite images from 1990.

Originally constructed to keep out enemies -- like China's Great Wall -- it's now a tourist attraction for humans astonished about how such a huge thing was built by such inferior creatures. The dam acts as a moat and protects the beavers from much of their land-based adversaries such as foxes and bears. In addition, the monstrous constructs also house several generations of beavers.

Photos.comNice beaver. (OK, that was the last one -- we swear.)

For reference, normal beaver dams clock in at around half the size of this one, but nonetheless, they can typically rival the Hoover Dam in length, which is pretty good for giant rats whose only method of construction is slapping things with their tails.

#6. Mile-High Termite Megacities

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Termites are probably more renowned for tearing down infrastructure than building their own, but the bastards that actually take up residence in your house are really just the lazy ones. In the wild, termites live in elaborate mounds built out of soil, mud, chewed wood and clumps of their own poop. Though the word "mound" doesn't quite do them justice, as each one is a 30-foot-tall self-sustaining megacity that can be seen on satellite images. When we said they are a "mile high" we of course mean that on termite scale -- as in, that's how massive these structures would be if humans were to build one.

istockphotoIn terms of scale, that would be six times bigger than your average Midwest town.

Underground, the termite colony can sprawl for several acres, and provides a self-sustaining city with everything the bugs need for survival. They even have little termite motel rooms just for mating.

Photos.comAnd it's totally flipping us off. What a dick.

The termites even farm their own resources. Colonies are equipped with underground farms where fungus is cultivated with collected plant matter. It's seriously like Hobbiton down there.

Most impressive is the fact that all of this is centrally heated. Not only do they build their towers facing north to south to regulate heat, tunnels throughout the mound serve as ducts to regulate the air flow and temperature of the colony, which is crucial to the upkeep of those cute little mushroom farms. To put this in perspective: Back when humans were still all living in huts made from mud and bark, the termites were already chilling out in enormous, air-conditioned arcologies. At this point, the only reason they don't simply take over the world is that we don't have anything they need.

istockphotoSome day our future overlords will rise

#5. Social Weaver Birds and Their Sky Condominiums

Social weavers are kind of the Hilton family of the bird world. Not only do they build the biggest nests of any bird, but the constructions are permanent -- housing hundreds of birds over several generations. And they actually rent out the extra rooms to birds of other species.

Their housing projects are as elaborate and decadent as any human condo, considering all of their decor is made of twigs. One pair of birds occupies each chamber, which is further subdivided into several rooms with entrances below the nest. The inner rooms retain heat and are used during the night, while the outside rooms are actually cooler than their surroundings and are used during the day. They'd have a large outdoor spa if they could figure out how to make the bubbles work.

Social weaver nests are so sturdy that they can last for hundreds of years, and the birds can even booby-trap the entrances with sharp sticks if they're vulnerable to snake infiltration. Life in the nest is so snug that other kinds of bird, even carnivorous pygmy falcons, are known to move in under the condition that they don't eat anybody.

GettyThey're like the YMCA for birds, and without the shower rape

#4. Gopher Towns

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You might think you learned everything you need to know about gophers from Caddyshack, the film classic in which Bill Murray is driven insane by a single gopher digging holes in his golf course. Surprisingly, this is misleading as a nature documentary, and if Murray's character knew what was really going on behind the scenes, he probably would have climbed a clock tower with a sniper rifle years before.

Photos.com"Is there a problem, asshole? That's what I thought. Walk away."

Gophers' burrows are really called "towns," owing to the fact that they can spread hundreds of acres and contain thousands of rodents at a time. They keep themselves relatively self-sufficient by hoarding an incredible amount of food from the area above, which they smuggle back into town inside their cheeks.

By Tim Gunther.And if that bird doesn't cool its shit, it's going to get itself smuggled.

Their underground tunnels are astonishingly well organized, with rooms for sleeping, for keeping warm in winter and even nurseries for junior gophers. On top of that, they (like the termites) have air chambers to regulate temperature. You might be thinking that an underground city is particularly susceptible to flooding, but the gophers have that covered. They actually build freaking levees around the entrances and laugh at any creature that hasn't developed the technology to withstand natural disasters.

On top of all this, your typical gopher town is as well protected from enemy invasion as Helm's Deep. The gophers have little watchtowers which are formed from the dirt they dug out of their tunnels. Gophers will stand on top of their mounds and silently watch for enemies.

When the gopher on duty (we assume they work in shifts) sees something suspicious, it sends a high-pitched whistle into the burrow and all the gopher archers and gopher berserkers arm the walls and brace the main gates. We only made some of that last part up.